Functional Devices RIBMX24 Series control relays are ideal for switching and controlling circuits from surges, voltage spikes and other electrical disturbances in the load circuit. These control relays are used in commercial buildings, industrial facilities, HVAC systems and lighting control systems. They are equipped with LEDs for showing real-time relay status. These functional devices are rated for a minimum of 10 million mechanical cycles, ensuring long service life. They have operating temperatures ranging from -30 to 140 degrees F.